This invention relates to an outboard motor and more particularly to an improved cooling system for outboard motors.
As is well known, outboard motors normally have their engines cooled by a liquid cooling system that draws water from the body of water in which the watercraft is operating and which discharges it back to the body of water after it has passed through the various cooling jackets of the engine and its auxiliaries. In this way, the body of water acts a heat exchanger for the engine.
Although the principle is quite simple, in practice, there are several problems in connection with such arrangement. One of these is that the cooling system, in addition to cooling engine cylinder block and cylinder head, frequently is employed for cooling also a portion of the exhaust system. Thus, the path of coolant must be chosen so as to provide the desired degree of cooling for the various components, particularly considering significantly different temperature characteristics that may arise in the various components that are cooled.
Because of the fact that outboard motors are frequently utilized in marine environments, corrosion can be a significant problem. This, coupled with the use of dissimilar materials in the engine and its auxiliaries, can give rise to galvanic corrosion problems. Therefore, it has been the practice to employ sacrificial anodes in the engine for the protection against corrosion.
However, due to the dissimilar materials and dissimilar conditions, a single anode positioned in the engine cooling jacket may not be adequate to protect the entire engine and auxiliaries which are cooled.
It is, therefore, a principal object of this invention to provide an improved anodic protection system for an outboard motor and its associated components.
It is a further object of this invention to provide an outboard motor cooling system that employs a plurality of anodes, each positioned and constructed to protect a specific part of the engine.
In conjunction with certain engine controls and for various other purposes, it may also be desirable to incorporate a temperature sensor that senses temperature in the coolant system. It should be apparent from the foregoing description, however, the temperature in the cooling system can vary significantly and be quite high in some areas. Thus, the temperature sensor may experience wide ranges of temperatures and can, therefore, become damaged.
Also because the water may drain at least in part from the engine cooling jackets when the engine is stopped the sensor temperature may become elevated, there is a danger the sensor may be overheated from the residual engine heat.
It is, therefore, a further object of this invention to provide an improved temperature sensing arrangement for the cooling system of an outboard motor.